Re: [PATCH net-next] r8152: use GFP_NOIO during system suspend

[Andrew Lunn]

On Fri, Aug 21, 2026 at 03:30:54AM +0000, Chih Kai Hsu wrote:
> > On Mon, Aug 11, 2026 at 02:03 AM +0800, Andrew Lunn wrote:
> > > On Mon, Aug 10, 2026 at 02:57:41PM +0800, Chih Kai Hsu wrote:
> > > > During system suspend, memory allocation with GFP_KERNEL can block
> > > > waiting for I/O to complete. If that I/O depends on a device that is
> > > > itself suspended, a deadlock results.
> > > >
> > > > Introduce RTL8152_SYSTEM_SUSPEND flag to track when the driver is
> > > > operating in the system suspend/resume context. Set the flag at the
> > > > start of rtl8152_system_suspend() and clear it at the end of
> > > > rtl8152_system_resume(), following the same pattern used by
> > > > SELECTIVE_SUSPEND for runtime suspend.
> > > >
> > > > In get_registers() and set_registers(), select GFP_NOIO when the
> > > > flag is set so that the kmalloc and kmemdup calls in those paths do
> > > > not trigger I/O reclaim.
> > >
> > > Do you have a reproducer for this? Or is it theoretical?
> > >
> > 
> > It is theoretical.
> > 
> > > > @@ -8693,6 +8700,9 @@ static int rtl8152_system_resume(struct r8152
> > *tp)
> > > >               usb_submit_urb(tp->intr_urb, GFP_NOIO);
> > > >       }
> > > >
> > > > +     clear_bit(RTL8152_SYSTEM_SUSPEND, &tp->flags);
> > > > +     smp_mb__after_atomic();
> > > > +
> > > >       return 0;
> > > >  }
> > > >
> > > > @@ -8758,6 +8768,9 @@ static int rtl8152_system_suspend(struct r8152
> > > > *tp)  {
> > > >       struct net_device *netdev = tp->netdev;
> > > >
> > > > +     set_bit(RTL8152_SYSTEM_SUSPEND, &tp->flags);
> > > > +     smp_mb__after_atomic();
> > > > +
> > > >       netif_device_detach(netdev);
> > > >
> > > >       if (netif_running(netdev) && test_bit(WORK_ENABLE,
> > > > &tp->flags)) {
> > >
> > > It seems odd to me that every driver needs to track if it is in
> > > suspend/resume or not. Doesn't the struct device tell you? Is there no global
> > state somewhere?
> > 
> > I found
> > https://elixir.bootlin.com/linux/v7.2-rc6/source/drivers/base/power/main.c#L
> > 2343
> > in the Linux source code.
> > 
> > pm_restrict_gfp_mask() is called before dpm_suspend(state). It removes
> > __GFP_IO and __GFP_FS from the global gfp_t gfp_allowed_mask. Therefore, I
> > think the driver can use GFP_KERNEL safely. Is this correct? Could you please
> > provide any advice?
> > 
> > 
> > >
> > >        Andrew
> > 
> > Best,
> > Chih-Kai
> 
> Hi Andrew,
> 
> Just a gentle ping on this patch.
> Based on my previous observation, should the driver use GFP_NOIO explicitly?

Please try to answer the question yourself. There are lots of drivers
out there. What do they do? What does the suspend/resume documentation
say?

	Andrew